add function to align groups of HelpContent, see phetsims/gravity-force-lab-basics#29 and phetsims/balloons-and-static-electricity#320
add function to align groups of HelpContent, see phetsims/gravity-force-lab-basics#29 and phetsims/balloons-and-static-electricity#320

phetsims/scenery-phet,phetsims/scenery-phet,phetsims/scenery-phet